DRIFT study of dinitrogen and dihydrogen adsorption on Li- AND Naforms of LSX zeolite.

摘要

Adsorption of molecular hydrogen at 77 K on Li-LSX zeolite with DRIFT control of perturbation of adsorbed molecules has discriminated three different types of adsorption sites with H-H stretching frequencies equal to 4062, 4084 and 4129 cm~(-1). Two first of these bands were ascribed to H_2 adsorption on Li~+ ions localized in supercages of the zeolite framework at S_(III) and S_(III)’ sites, while the latter band most likely belongs to H_2 adsorption on hydrogen groups and Li~+ ions at SII sites. Adsorption of N_2 by Li~+ ions at S_(III) and S_(III)’ sites is the strongest resulting in a decrease of intensity of the corresponding DRIFT bands from adsorbed H_2. N_2 dsorption by Li~+ ions at S_(II) sites is very much weaker. Adsorption of N_2 by Na~+ ions at S_(III) sites in Na-SLX zeolite is also stronger than by sodium ions at SII sites.